This map illustrates an analysis of the evolution of satellite-detected surface waters in Bayelsa State, Nigeria, based on satellite data recorded on 16, 21, 22, 28 September and 03 October 2018. Before the national flood had been declared by the government of Nigeria on 18 September 2018, a total surface of 79,902 ha was detected as inundated within Bayelsa State, as of 16 September 2018. On 21 and 22 September 2018 an additional surface of 5,280 ha inundated areas were detected, representing an increase of the surface waters of 7%. On 28 September 2018, a total surface of 86,900 ha was detected as inundated, representing an increase of the surface waters of 2%. Then, on 03 October 2018, the water extent had increased by 4%, a total of 90,583 ha detected as inundated. According to the Worldpop data and the satellite detected waters from Sentinel-1 images, the total population affected by the floods rose from approximately 105,000 to 145,000. This is a preliminary analysis and has not yet been validated in the field. Please send ground feedback to UNITAR - UNOSAT.